This section provides background information related to the present disclosure which is not necessarily prior art.
In a lighting apparatus using a PN junction light-emitting element, a light-emitting diode (LED) module having a plurality of LEDs mounted on a power transmitting substrate is typically used as a light source. The LEDs have the advantages of small size, low power consumption and excellent control characteristics, and therefore the LED lighting apparatus can be made slim and lightweight. However, a typical LED lighting apparatus includes a heat sink for heat dissipation or a separate drive circuit for driving an LED module. Elements such as the heat sink or the drive circuit make it difficult to realize a slim and lightweight design of the LED lighting apparatus.
For example, the drive circuit may include an A/D converter to supply DC power, and the A/D converter includes a trans-coil for lowering the voltage of AC. The trans-coil has a drawback in that, since the trans-coil is arranged occupying a large space in the drive circuit, the dimension of the product having the same becomes large.
Meanwhile, since the LED module includes a plurality of LEDs, the overall current capacity becomes large. Thus, the conventional LED drive circuit employs an electrolytic capacitor as a part. Such an electrolytic capacitor is suitable for a circuit with high capacitance, but its poor frequency characteristics and relatively high aging degradation reduce the reliability of the circuit. Particularly, in the case of an electrolytic capacitor being mounted, together with an LED, on a power transmitting substrate, the lifespan of the electrolytic capacitor is much shortened due to heat generated by light emission of the LED. Additionally, as the volume of an inductor and a capacitor increases in a circuit having a plurality of LEDs arranged thereon, this may even cause limitations to the exterior design of an LED lighting apparatus.
Moreover, the outer appearance of a lighting apparatus generally varies according to general classification of lamps, such as an incandescent lamp type and a fluorescent lamp type, and has various shapes according to use and place. Accordingly, the shapes of an LED module, a heat sink and a drive substrate also vary with such various shapes. In addition, lighting apparatuses of various shapes are each provided depending on a specific installation environment. Due to this, the lighting apparatus becomes less compatible according to use and place and its installation becomes difficult.